Oil circulating and feeding system



1947! J. J. SERRELL ET AL 3 OIL CIRCULATING AND FEEDING SYSTEMFiled'July 4, 1942 3 Sheets-Sheet 2 v n a a. WFMAWMMIP 9. 5 iii. a a P 1mvazvroas Leo D-Jon John 15a .8) W 0,.W

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ATTORNEY 1947- J. J. SERRELL 'Erm. 2, 32,13

on. cIRcuLATme AND FEEDING sYsTBu Filed July 4, 1942' s Sheets-Sheet sawn/Tons Leo D.Jones.

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ATTORNEY Patented Dec. 9, 1947 OIL CIRCULATING AND FEEDING SYSTEM JohnJ. Serrell and Leo D. Jones, Philadelphia, Pa., assignors to TheSharples Corporation, Philadelphia, Pa., a corporation of DelawareApplication July 4, 1942, Serial No. 449,830

9 Claims. (Cl. 184-6) The present invention pertains to a centrifugalapparatus for deaerating liquids and to the combination of such anapparatus with other features of a lubrication system. While features ofthe invention may be used in a variety of applications, they will bedescribed for purposes of illustration and convenience in their relationto the lubricating system of an aviation engine, since that is thepurpose for which they were originally conceived.

The lubricating system of an airplane engine consists of an oil storagetank, a conduit from the storage tank to the engine, a feed pump on orin the engine for pumping oil to the various parts of the engine tolubricate it, a sump in the engine into which the oil drains from thevarious parts of the engine, a scavenge pump for pumping oil from thesump, a conduit from the scavenge pump to an oil cooler, an oil coolerand a conduit back to the oil storage tank. The system may includeadditional items such as a relief valve to by-pass oil around the coolerunder certain conditions, a thermostatic valve for accomplishing thissame purpose, and/or a centrifugal separator for purifying the oil afteruse, but the elements discussed above are the essential ones, insofar asthe system of the present invention is concerned.

The scavenge pump ordinarily has a displacement from two to three timesas great as the oil feed rate of the feed pump in the case of radialengines, and in the case of in-line engines, there are usually twoscavenge pumps, one at each end of the crank-cases, each of these pumpshaving a displacement at least twice as great as that of the feed pump.This relationship of capacities between the scavenge pump or pumps andfeed pump is necessary to insure the continuous removal of all of theoil which drains into the sump. A necessary incident to th srelationship, however, is the fact that vapor from the crankcase ispumped by the scavenge pump or pumps together with the oil through theoil cooler and into the storage tank. 1 The pumping of this vaporthrough the oil cooler increases the drop in pressure through the coolerand the load on the scavenge pump or pumps, and complicates the problemof cooling the oil. The pressure drop through the cooler causes finerdispersion of the vapor and thus aggravates the foaming problem to bediscussed hereinafter.

The vapor carried into the oil stream through the scavenge pump alsocomplicates the problem of introducing the oil into the storage tank. Ifthe oil containing this vapor is introduced 2 beneath the surface of theoil already in the tank, the vapor passes upwardly through the body ofoil and causes a foam. If, on the other hand, the oil containing thevapor is introduced above the level of the oil in the storage tank, theresulting splashing also causes foam.

The presence of the vapor in the oil from the scavenge pump adds to thedifllculty of solving two other problems. The first of these is the feedof oil to the feed pump when flying at high elevation. The maindifllculty here is the lack of atmospheric pressure to force oil fromthe storage tank to the inlet of the feed pump. This difficulty isaggravated by the air bubbles entrained in the oil, since these airbubbles seriously impair fiow of oil to the feed pump at highelevations. Another problem is that 0! feed of oil to the feed pump inmaneuvers which cause a negative G in the plane, such as flying invertedand 20 performing outside loops. Here again the natural problem causedby these maneuvers is accentuated by the presence of the vapor in theoil.

The present invention includes features for solution of each of theabove-discussed problems.

It includes a system in which the oil is fed, under pressure derivedfrom the energy imparted to it by the scavenge pump, from that pump to apoint adjacent the zone of discharge of oil from the oil storage tank. AVenturi connection is provided at this point, with the result that theoil passing from the motor is passed toward the suction side of the feedpump under energy derived from the scavenge pump, while additional oilis sucked from the oil storage tank toward the feed pump under theimpelling effect'of said Venturi connection. 7

In the preferred form of the invention, the oil is subjected totreatment in a centrifugal de aerator to remove most of the vaporssucked into the oil by the scavenge pump, during its passage from thescavenge pump to the Venturi connection referred to above. Thecentrifugal deaerator may be mounted in advance of an oil coolerinterposed between the scavenge pump and the oil storage tank, or it maybe mounted beyond the oil cooler in the line of flow of the oil, as forexample, by being mounted in the oil storage tank itself. If mounted inadvance of the cooler, the operation of the cooler is rendered moreeflicient by removal of the vapor at this point, and the emulsifyingaction to which the oil and air are subjected in passing through thecooler is also avoided.

In the preferred form of the invention, the centrifugal deaeratorconsists of a non-rotating tank around the interior surface of which theoil flows in a rotating motion during its passage from entrance to exitof the tank in a longitudinal direction. This tank is preferablyprovided with a valve controlling discharge of gas or vapor from acentral portion of the tank, after removal of this gas or vapor underthe influence of centrifugal force, and the opening and closing of thisvalve are controlled by the thickness of the layer of liquid passingalong the interior wall of the deaerator. Thus, when the wall of liquidexceeds a predetermined thickness, the actuating mechanism moves thedeaerator valve to a position preventing discharge of gas from the tank,and when this wall recedes again to a permissible thickness, the valveis again opened and discharge of gas resumed.

A better understanding of the details of the invention will be had byreference to the following description in the light of the attacheddrawing, in which,

Figure 1 is a flow sheet illustrating the arrangement of the deaeratorand venturi in accordance with one form of the invention,

Figure 2 is a sinniar view illustrating an arrangement involving analternative,

Figure 3 is a cross sectional view through a preferred form ofdeaerating apparatus,

Figure 4 is a plan view of the apparatus of Figure 3 with parts brokenaway to illustrate a valve detail, and

Figure 5 is a diagrammatic view of a simplified form of deaeratormounted directly in the oil storage tank, this view containing also adetailed illustrati'on of the Venturi connection for assisting in feedof oil to the suction side of the feed pump.

Referring to the drawing by reference characters, it will be seen thatFigure 1 illustrates an arrangement in which the oil is sucked from theengine ill by a scavenge pump II, which is shown for the purposes ofconvenience as separate from the engine Ill, although it is ordinarilydirectly associated with the engine. From the scavenge pump I I, themixture of oil and gas passes to the centrifugal deaerator [2, fromwhich vapor is discharged at i3, while the oil is passed, under energyderived from the scavenge pump, through a cooler l3.

Oil from the cooler I3 is then passed through conduit H, which mayinclude a portion passing directly through oil storage tank l5 to aVenturi,

connection ii,

The Venturi connection l6 communicates with the main body of oil in thestorage tank l5 adjacent the zone of discharge of oil from the main bodythereof in said tank, and thus provides suction for impelling oil fromthe main body thereof in said tank, together with oil from the conduitl4, through the conduit I! to the feed pump it by which this oil isreturned to the engine I for re-use.

It will be seen that, in such a system, by centrlfugally deaerating theoil and returning this centrifugally deaerated oil to the engine, thedisadvantage of feeding large quantities of gas, together with the oil,to the engine, is avoided- It will also be seen that, by passing the oilfrom the tank i5 to the feed pump l8 under the suction effect of theVenturl connection l8, disadvantages previously encountered inconnection with feed of oil from the storage tank to the engine areavoided.

Figure 2 of the drawing illustrates a somewhat modified arrangement inwhich the deaerator is mounted between the cooler and the Venturi con- 4nection, instead of being mounted in advance of the cooler. As hereillustrated, the deaerator may be mounted directly within the oilstorage tank. In this embodiment of the invention oil from the engine ispassed by scavenge pump 2! through cooler 22 to the deaerator 23,through conduit 24. Oil from the rotating body thereof in the deaerator23 is passed, under energy derived from the scavenge pump, throughVenturi connection 26, and in passing through this connection, it sucksoil from the tank 25 through the conduit 21 to the feed pump 28. Sincethe general principles of this form of the invention are similar tothose of that described above in connection with Figure 1, furtherexplanation is deemed unnecessary.

Figures 3 and 4 illustrate a preferred form of deaerator for use in thesystem of either of Figures 1 and 2. As here illustrated, the deaeratorconsists of a tank provided with an interior surface 3| which ispreferably circular, and which may be cylindrical or frusto-conical asshown. This tank is provided with an inlet connection 32 for injectingoil tangentially into the tank along the surface 3| in a directionhaving a longitudinal component toward the tangential outlet 33 whichreceives the oil after the gas has been separated by centrifugal forcedue to rotating movement of the oil during passage along surface 3| fromentrance to exit.

The tank 30 is provided with an end plate 34, which is removably mountedto permit access to the interior of the tank. This end plate is providedwith a central opening to receive a housing 35 for a packing gland, thishousing being secured to the end plate by bolts 36. A hollow tube 31 isslidably mounted in a central bore of the housing 35, the upper end ofthis tube extending to a position within the tank 30, and this positionbeing adjustable by longitudinal movement of the tube.

A packing gland 38 surrounds the tube 31 within the bore ofthe housing35, and the prevention of leakage and longitudinal securement of thetube in the desired position are both accomplished by tightening of thegland nut 39.

Tube 31 is provided with a nipple 40 at its lower end for connection toother piping, and this piping may extend through the outer surface ofthe tank 25 in case the deaerator is mounted Within that tank asillustrated in Figure 2 of the drawing. A valve 4| is secured in slidingrelationship upon the upper end of the tube 31, and the upper end of thevalve is urged downwardly and held in contact with the upper end of thetube 31 by the spring 42. The lower end of the spring 42 is secured inposition longitudinally with respect to the tube 31 by the nut 43, whichmay be locked by nut 44, both of these nuts being threaded to the tube31. These nuts provide a method of securing the spring in positionlongitudinally, and also a method of altering the tension on the spring,as will be evident from inspection of the drawing. A stop pin 45 issecured to the tube 31 adjacent the bottom of the valve 4 I, and thisstop pin coacts with an abutting surface 46 of the lower end of thevalve to secure the valve in open position under the influence of thespring 42 until accumulation of -a predetermined thickness of an annularlayer of liquid along the interior of the wall 3i, as will be evidentfrom further discussion of details by which this result is accomplished.A plurality of wings 41 extend outwardly from the cylindricallyextendingportion of the outer surface of the valve 4|, and this valve is alsoprovided with a cylindrically extending p rtion 63 I above the upper endof the tube 31, in order to minimize leakage of oil into the tube 31 bysplashing. When the abutment 46 is in contact with the pin 45, anopening 48 in the upper, otherwise closed, end 49 of the valve 4|registers with an opening in the upper end of the tube 31 to permitdischarge of gas through these registering openings and the tube 31.When the abutment 46 is moved in a counterclockwise direction away fromthe pin 45, on the other hand, these openings are brought out ofregistry with each other, with the result that the valve connectionandpossibility of discharge of gas through the tube 31 is closed, muchafter the fashion of a talcum powder can.

In the operation of the above apparatus, the mixture of air and oilenters through the tangential inlet pipe 32. The mixture flows aroundthe inner wall 3| f the tank 30, during its passage from the inlet 32 tothe outlet 33, and this rotating flow causes separation of air towardthe center of the tank under the influence of. centrifugal force. Afterbeing relieved of its air in this manner, the oil leaves the tankthrough the tangential outlet 33. The air flows through the hole 48 andregistering hole in the top of tube 31, and escapes from the apparatusthrough this tube. So long as the valve is maintained in open positionby the action of the spring 42 in holding the abutment 46 against thepin 45, the air will discharge rapidly through the valve and tube 31.During this operation, the thickness of the body of oil rotating withinthe surface 3| during its passage longitudinally along that surface willgradually increase until the inner surface of this layer strikes thewings 41 and causes these wings to move in a counter-clockwise directionagainst the influence of the spring 42. This rotary movement of thewings 41 under the impelling effect of the rotation of the body of oilwithin the tank causes the openng 48 to be moved out of registry withthe coacting opening in the otherwise closed upper end of the tube 31,and prevents further discharge of air so long as this conditioncontinues to prevail. As the operation continues after this condition isreached, the pressure in the central part of the tank 30 will increase,due to the fact that the released air cannot be discharged through thetube 31, and this increase in pressure will cause an increase in theamount of oil discharged through tangential outlet 33, with the resultthat the amount of discharge will ultimately exceed the amount of feed,and the inner surface of the stratum of oil within the surface 3| willagain recede. When this happens, the spring 42 will again return thevalve to open position, with the result that the air can again bedischarged through tube 31.

The above description of the operation of the centrifugal deaeratingapparatus is somewhat idealized for the sake of simplicity ofexplanation. As a matter of fact, in the actual operation of theapparatus, the valve may not be moved completely either to absolutelyclosed or absolutely open position, after the operation is well underway. This valve moves to an intermediate position after a conditionfairly close to equilibrium is established between the effect of thespring 42 in moving the valve to open position and the efiect of wings41 in moving it to closed position. As a matter of practical operation,however, the efiect of the valve in permitting discharge of gas, butpreventing discharge of liquid through tube 31 by preventingaccumulation of too deep a stratum of liquid within the tank is thesame, regardless of whether the valve actuating mechanism eflects actualsuccessive closing and opening of the valve,

or merely the attainment of an equilibrium condition which builds up apressure within the center of the tank sufllcient to bring the rate ofdischarge of oil through conduit 33 to the approximate rate of feedthereof through the conduit 33.

Figure 5 of the drawing illustrates a centrifugal deaerating apparatusespecially adapted to be mounted within the oil storage tank, asillustrated in Figure 2 of the drawing. As here illustrated. the oilfrom the scavenge pump enters the tank 25 through an inlet connectionand is discharged tangentially along the inner wall of the cylinder 6|of the centrifugal deaerating apparatus 23. A plurality of wings 62 maybe mounted for free movement in a rotary direction with respect to thecylinder 6| by means of bearing connections 63 through which these wingsare secured in position relative to the supports 64 by which thecylinder 6| is held in position in the tank 25. Oil which passestangentially into the interior of the cylinder 6! flows in a rotarymotion around that cylinder during its passage downwardly along thecylinder from the inlet connection 60 to the outlet connection 65through which it is tangentially discharged from the cylinder. Duringthis movement, the wings 62 tend to stabilize the rotary movement of theoil within the cylinder 6 I. In being discharged tangentially from thelower end of the cylinder iii, the oil is impelled through the outletconnection 65 under energy initially derived from the scavenge pump. Theoutlet connection 65 conducts the oil to a portion of the tank 25adjacent the zone of discharge of oil from that tank, and thisconnection is restricted, as i1- lustrated at 66, in the form of thecontracting end of a Venturi throat. The expanding end 61 of the Venturimay constitute an extension on the outlet from the tank 25, and space isprovided as indicated at 63 between the outlet end 66 of connection 65and the inlet end of connection 61, in order to permit oil to be suckedthrough this Venturi connection from the main body of the storage tank,and passed to feed pump 28 along with oil being recirculated fromcylinder 6| to this feed pump. This connection is illustrateddiagrammatically in Figure 2 of the drawing, and a similar arrangementwith respect to the flow diagram of Figure 1 of the drawing is alsoillustrated in connection with that embodiment of the invention in thatfigure. As discussed above, by sucking the oil from the oil storage tankin this manner, and by deaerating the oil before recycling it,dificulties in feed of oil to the motor due to causes discussed aboveare largely eliminated.

Various modifications are possible within the scope of the invention,and we do not therefore wish to be limited except by the scope of thefollowing claims.

We claim:

1. In an oil circulating and feeding system for motors, the combinationcomprising, scavenge pump for removing oil from the motor, a centrifugalgas separator in the line of flow of oil from the scavenge pump, meansfor conducting oil under energy derived from said scavenge pump to apoint adjacent the zone of discharge of oil from an oil storage tank, aVenturi connection between said conducting means and said storage tankadjacent said zone of discharge, a feed pump for impelling oil to saidmotor, and a conduit connecting said feed pump with said Venturiconnection.

2. In an oil circulating and feeding system for motors, the combinationcomprising. scavenge pump means for removing oil from the motor,.an oilstorage tank, a feed pump for feeding oil to the motor, means forconducting oil under energy derived from said scavenge pump to thesuction side of said feed pump, means for directing. oil

.flowing from said storage tank to the feed pump ,scavenge pump, whilesupplementing said oil supply with oil from said storage tank, saidscavenge pump being driven by a source of power independent of thatproduced by the impelling of oil by said feed pump.

3. In an oil circulating and feeding system for motors, the combinationcomprising, a scavenge pump for removing oil from the motor, an oilcooler in the line of flow of oil from the scavenge pump, a centrifugalgas separator in the line of flow or oil from the scavenge pump and saidoil cooler, said centrifugal gas separator being located beyond said oilcooler in the direction of flow of oil from said scavenge pump, meansfor conducting oil under energy derived from said scavenge pump to apoint adjacent the zone of discharge of oil from an oil storage tank, aVenturi connection between said conducting means and said storage tankadjacent said zone of discharge, a feed .pump for impelling oil to saidmotor, and a conduit connecting said feed pump with said Venturiconnection,

4. In an oil circulating and feeding system for motors, the combinationcomprising, a scavenge pump for removing oil from the motor, acentrifugal gas separator in the line of flow of oil from the scavengepump, an oil cooler in the line of flow of oil from said scavenge pumpand said centrifugal gas separator, said oil cooler being located beyondsaid centrifugal gas separator in the line of flow of oil from saidscavenge pump, means for conducting oil under energy derived from saidscavenge pump through said oil cooler and to a point adjacent the zoneof discharge of oil from an oil storage tank, a Venturi connectionbetween said conducting means and said storage tank adjacent said zoneof discharge, a feed pump for impelling oil to said motor, and a conduitconnecting said feed pump with said Venturi connection.

5. An oil circulating and feeding system as defined in claim 3, in whichsaid centrifugal gas separator is mounted directly in the oil storagetank. 6. An oil circulating and feeding system as defined in claim 3, inwhich said centrifugal gas separator comprises a stationary tank throughwhich the oil is passed in a, rotating motion, said stationary tankbeing mounted directly in the oil storage tank, and having an outlet forgas removed from the main body of the oil which is connected to the mainstorage space of said tank. 7. In an oilcirculating and feeding systemfor motors, the combination comprising, a scavenge pump for removing oilfrom the motor, means for conducting oil under energy derived from saidscavenge pump to a point adjacent the zone of discharge of oil from anoil storage tank, a Venturi connection between said conducting means andsaid storage tank adjacent said zone scavenge pump designed to receiveand discharge said oil under pressure derived from the energy ofsaidscavenge pump, an oil storage tank, a feed pump for feeding oil tothe motor, means for conducting oil under energy derived from saidscavenge pump to and through said gas separator and from said gasseparator to and through a zone of confluence with oil flowing from saidstorage tank to said feed pump, said zone of confluence comprising anejector connection for a8- sisting in removal of oil from said storagetank, and thereby supplying deaerated oil to said feed pump under energyderived from said scavenge pump, while supplementing said oil supplywith oil from said storage tank.

9. In an oil circulating and feeding system for motors, the combinationcomprising, scavenge pump means for removing oil from the motor, a gasseparator in the line of flow of oil from said scavenge pump designed toreceive and discharge said oil under pressure derived from the energy ofsaid scavenge pump, an oil cooler in the line of flow of oil from saidgas separator also designed to receive and discharge said oil underpressure, an oil storage tank, a feed pump for feeding oil to the motor,and means for conducting oil under energy derived from said scavengepump to and through said gas separator and oil cooler and to said feedpump through a zone of confluence with oil flf n said storage tank, saidzone of confluence comprising an ejector connection for assisting inremoval of oil from said storage tank, and thereby supplying oil to saidfeed pump under energy derived from said scavenge pump, whilesupplementing said oil supply with oil from said storage tank.

- JOHN J. SERRELL.

- LEO D. JONES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,893,040 Schmidt Jan. 3, 19332,323,525 Ebel July 6, 1943 1,432,817 Wertzheiser Oct. 24, 19221,622,278 Boyd Mar. 29, 1927 2,024,336 Cavanaugh Dec. 1'7, 19352,316,729 Tryon Apr. 13, 1943 2,268,653 Flowers Jan. 6, 1942 1,440,808Wineman Jan. 2, 1923 2,147,993 Scheibe Feb. 21, 1939 1,766,666 MeyerJune 24, 1930 FOREIGN PATENTS Number Country Date 512,991 Great BritainOct. 2, 1939 493 553 Great Britain Oct. 11, 1938 692,505 Germany June21, 1940 359,401 Great Britain Oct. 12, 1931 553,569

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